The present invention relates to a packaging apparatus in which a continuously transferred film is gripped and heat-sealed by a pair of seal rollers.
Known examples of conventional filling/packaging machines for automatically filling and packaging such products as liquids, powders or viscous substances are described in Japanese Unexamined Patent Publication Nos. 2-46265 and 2-32929 published by the Japanese Patent Office. In such a apparatus, a portion of a film which is drawn out of a film web roll and continuously transferred is folded, both margins of the folded portion of the film are overlapped and vertically sealed by a pair of vertical seal rollers, a product is filled into the vertically sealed tube-shaped portion of the film, and the film is laterally sealed by a pair of lateral seal rollers, whereby bags containing the product are successively formed.
A film of a large length is generally used as a film web, which is a roll of the film used for packaging, to save the labor required for replacing the film and thereby allow for a high packaging work efficiency. For reasons related to the manufacture of such elongate film webs, a plurality of film strips of a specific length are joined together with tape, for example, to obtain a single film web.
As a consequence, film joints where the above-mentioned film strips are joined together occur in the film web during packaging operation. These joints are places where the film is interrupted and patches of the tape or other splicing parts are attached. Thus, when the packaging apparatus vertically seals the film by using the vertical seal rollers or laterally seals the film by using the lateral seal rollers, the tape or the like could become entangled between the seal rollers and, in certain cases, the tape or the like at the joints could melt and adhere to the seal rollers. Should this situation occur, it is likely to adversely affect subsequent sealing conditions.
A bag blank including such a film joint not only produces an awkward appearance but gives rise to a possibility that the filled product leaks from the bag blank. The bag blank of this kind should therefore be handled as a defective one, and there has been a demand to prevent leakage of product contents and a consequent damage to the apparatus.
In the light of the foregoing, it is an object of the present invention to provide a packaging apparatus which makes it possible to maintain good sealing performance by keeping joints of a film from being entangled to rule out the possibility of adhesion of a molten material to seal rollers, easily remove portions of the film including the joints as defective parts, and prevent leakage of product contents through the joints to keep thereby the packaging apparatus clean.
A film is drawn out from a film roll and continuously transferred, and margins of the film are overlapped and vertically sealed by paired vertical seal rollers to shape the film into a tubular form. A product content is filled into a tube-shaped portion of the film, and the tube-shaped portion of the film is laterally sealed by paired lateral seal rollers to thereby form a bag. A packaging apparatus is constructed such that at least one of the lateral seal rollers is movably provided and the packaging apparatus comprises a pusher for at least one seal roller against the other seal roller, a joint detector provided upstream in a film transfer direction of the paired lateral seal rollers for detecting a joint in the film, and a controller which reduces or eliminates a pushing force exerted by the pusher when a specified time period has elapsed after detection of the joint in the film by the joint detector. In this construction, the pushing force exerted by the pusher for the lateral seal rollers is eliminated when the specified time period has elapsed by the aforementioned joint detector.
As a result, sealing blades of the seal rollers are separated from each other and, thus, the joint is allowed to pass through without being laterally sealed, so that it is possible to prevent a molten material of the joint from adhering to the sealing blades of the seal rollers causing a subsequent deterioration in sealing performance.
The aforementioned controller reduces or eliminates the pushing force of the paired seal rollers for a specified time period after the joint detector has detected the joint in the film, and returns the paired seal rollers to their pushing condition so that they can grip and heat-seal the film after allowing the joint to pass through by advancing the film. For the controller of the packaging apparatus in this way, only a portion of the film including the joint is allowed to pass and heat seal operation is resumed subsequently, it is possible to carry out continuous packaging operation without stopping the feeding of the film.
Furthermore, the aforementioned controller calculates arrival time required by the joint to arrive at the seal rollers after the joint detector has detected the joint in the film, and reduces or eliminates the pushing force exerted by the pusher before the arrival time elapses. Since the packaging apparatus can be constructed so as to set timing at which the pushing force of the pusher for pushing the seal rollers is reduced or eliminated or timing at which the pushing force is recovered based on the calculated arrival time, the seal rollers can be separated from each other in such a way that they do not heat-seal only the portion of the film including the joint.
A packaging apparatus in which a film is drawn out from a film roll and continuously transferred, and while the film is gripped and heat-sealed by paired seal rollers to form a bag, a product content is filled into the bag by a product feeder comprises a joint detector provided upstream in a film transfer direction of the product feeder for detecting a joint in the film, and a controller which interrupts feeding of the product content by the product feeder when a specified time period has elapsed after detection of the joint in the film by the joint detector. Since the feeding of the product content is interrupted when the specified time period has elapsed detection of the joint in the film by the joint detector so that the product content is not fed into a portion of the film including the joint, it is possible to prevent leakage of the product content.
A packaging apparatus in which a film is drawn out from a film roll, margins of the film which is continuously transferred are overlapped and vertically sealed by paired vertical seal rollers to shape the film into a tubular form, a product content is filled into a tube-shaped portion of the film, the tube-shaped portion of the film is laterally sealed by paired lateral seal rollers, and a laterally sealed portion is cut by a cutter to thereby form a bag comprises a joint detector provided upstream in a film transfer direction of the cutter for detecting a joint in the film, and a controller which disables the cutter from performing its cutting operation when a specified time period has elapsed after detection of the joint in the film by the joint detector. Since a bag including a joint is not cut but allowed to proceed continuously, such a bag can be rejected as a bag having a fault from ordinary bags.